The invention is in the field of tape feeders in general by which a tape is advanced stepwise to sequentially present components to a pick-up station where the component is removed from the tape for subsequent handling, such as transfer to a conveyor or a circuit board.
Particularly, the invention is directed to feeders for stepwise indexing of tapes having pockets containing surface mountable electrical components. Typically, a top cover of the tape is peeled sufficiently from the substrate so as to open each pocket in turn, and thus provide access to the component therein. Auxiliary covers or movable "shutters" often are provided to prevent loss of components from opened pockets.
Several types of supply tapes are used presently, and the invention is applicable to these and other component supply tapes. One tape has a plastic substrate embossed to define component holding pockets which are enclosed by a separable thin plastic top cover; another tape has holes all the way through a cardboard substrate with top and bottom covers for the holes so as to define the component pockets.
The prior art cross-referenced above generally discloses peeling of the tape cover by indexing a take-up reel along with indexing of the component supply tape, wherein the cover is passed around a fixed guide surface and maintained under tension by the take-up reel. Although the apparatus of the invention is particularly adapted to a peeling mechanism which is different from these cross-references, the concepts of step length adjustment and interchangeable supply and peel assemblies of the invention are equally adaptable to the prior art.
The majority of the prior art tape feeders utilize indexing wheels having pins on the periphery thereof which are engagable in the indexing holes of the supply so as to feed the tape stepwise by rotation of the wheel. Such stepwise rotation is usually accomplished by means of a rack and pawl-type of arrangement wherein the pawl is engaged in a tooth of the rack and moved to advance the rack by one indexing step. Heretofore, the stepping length of indexed feeding by the wheel has been adjustable by removing and relocating a pin which determines whether the pawl engages every rachet tooth or every other rachet tooth. Rather than skipping a rachet tooth to increase the length of feeding step, the prior art has also engaged two consecutive rachet teeth by the pawl, for each step, such that each step actually comprises two half steps.
It is also known to have a belt driven indexing wheel driven by a motor wherein a bit switch of a circuit board is selected to determine a number of revolutions of the motor per indexing step.
In the industry involved, tape feeders are generally "bricked" together side-by-side to provide the maximum amount of feeders in a minimum amount of space and generally it is necessary to remove a feeder in order to change the stepping length and/or the supply tape. If a jam or breakage of the tape occurs with the prior art, it also generally is necessary to remove and replace the entire feeder assembly or to shut it down for an uneconomical length of time necessary to clear the jam or to rethread the tape in the feeder and/or the cover material into the peeler.
The instant invention overcomes these various problems in a unique manner, and these and other advantages and objectives of the instant invention will become apparent from the following detailed disclosure.